400 bad request for http m-post method (no replies)

Hi,
I'm getting the below error in nginx reverse proxy server. It seems the proxy server does not recognize the http method: "M-POST" ? Is there a way i can allow these incoming requests ?

nginx.1 | xxxx.xxx.xxx 10.x.xx.x - - [05/Oct/2016:10:31:57 +0000] "M-POST /cimom HTTP/1.1" 400 166 "-" "-"
nginx.1 | xxxx.xxx.xxx 10.x.xx.x - - [05/Oct/2016:10:31:57 +0000] "M-POST /cimom HTTP/1.1" 400 166 "-" "-"



Thanks in advance.